Fig. 2.

Estimated instrumentation effects of “Yes” and “No” outcomes. For each of three different vaccines, Fig. 2 reports the estimated effects when varying the number of response options (left column) and the response order (right column). These estimates correspond to coefficients β̂Unsure and β̂NoFirst from Eq. (1), respectively. Initial COVID-19 vaccine intentions were reported by those without COVID-19 vaccination (n = 3,698). Those who were vaccinated against COVID-19 (n = 110) were asked to report their intentions to receive the COVID-19 booster and influenza vaccine. Note that the error bars represent the 95% confidence interval for the corresponding estimate.